MAPT and early-onset autosomal dominant Alzheimer disease: Moreover, earlier studies found tau fragmentation to be primarily associated with degradation of the fuzzy filament coat.25, 26 Full-length tau is the major component of the paired helical and straight filaments of Alzheimer's disease.27 On the other hand, truncation of tau increases its propensity to aggregate and it has been suggested that cleaved tau may seed the aggregation of the full-length protein.28, 29, 30 Taken together, it is therefore possible that truncation of a small amount of tau can lead to its aggregation and the seeding of full-length tau.